Retarding device for time-limit relays



T. T. GREENWOOD RETARDING DEVICE FOR TIME LIMIT RELAYS Filed 511116.17,1918 Patented Aug.. 7, 1923.

uniransrarss TnLMn T. GREENWOOD, or EAST TEMPLETON, MASSACHUSETTS,ASSIGNOP. To s. n. eONoT, JP... or BnooxLrNn, MASSACHUSETTS.

RETARDIMNG DEVICE FOR TIME-LIMIT RELAYS.

Application filed June 17, 1918.

To all whom t may concern: y Y i Be it known that I, TALMA T. GREENWOOD,a citizen of the United States, residing at East Templeton, in thecounty of Worcester and State of Massachusetts, have invented animprovement in Retarding Devices for Time-Limit Relays, of which thefollowing is a speciiication.

My invention relates to time limit relays adapted for the protection andcontrol of electric circuits and apparatus connected thereto.

The invention has particular reference to time limit relays having aflexible or yielding diaphragm which is actuated by the plunger of asolenoid to force air through an orifice, the rate of flow of airthrough said orifice determining the time element of the relay.

The object of my invention is in the provision of a relay which issimple and inexpensive in design and construction, and which is positiveand reliable in, operation.

Fig. 1 is a sectional elevation of a relay embodyingrv my invention.

Fig. 2 is a side elevation of the relay.

F ig. 3 is a plan view of the relay.

Fig. l is a modified form of diaphragm.

Figs. 5 and 6 are modified forms of diaphragm engaging members.

ills here shown the relay comprises the solenoid or coil 10 which isarranged within the casing 12 formed of magnetic material, and which hasa top pole piece 13 extended within said coil vand magneticallyconnected with said casing 12.

The solenoid or coil 10 is Wound upon, or is provided with, a centraltube 14, ofbrass or other non-magnetic material in which is slidablyarranged a similar tube 15. fr core or plunger 16 is disposed withinsaid tube 15 and is adjustable therein to vary the current value atwhich the solenoid will operate by means of a'screw threaded end cap 1 7which fits in similar threads of the tube 15. A rod 118 is secured inthe upper end of said tube 15 and slidably extended through the top polepiece 13 of the solenoid and serves as means whereby a movement of thecore is transmitted to the time element of the relay.

Serial No. 240,385.

The time element includes a cup shaped pot 19 which is disposed abovethe solenoid and supported in such position, by the standard 20., Aflexible or yielding diaphragm 21, which forms an object of myinvention, is secured over the cup shaped end of said pot 19, in anysuitable manner, such for instance, as by means of thelhelical springs22. A diaphragm-engaging mem-r ber 23, suitably curved to conform to thecupped end of the pot 19 is secured to the .centre of said diaphragm 21,and when moved upward by the movable element of the solenoid serves toforce said diaphragm into said cup shaped opening. Thediaphragm-engaging member 23 is secured at substantially its centralportion, to a downwardly extending stein 241 which has a central recess25 in which the rod 1S of the movable element of the solenoid isslidably arranged.

Said rod 18 is provided with a flange 26 pinned or otherwise securedthereto between which and the bottom of a recessed opening 27 in saidstem a spring 28 is arranged and through which movement of the movableelement of the solenoid is transmitted to the diaghragm-engaging member.This arrangement of yielding connection of the movable element of therelay and the kdiaphragm-engaging member of the time element providesmeans whereby a substantial uniform pressure may be exerted against thediaphragm of the time element regardless of the varying energir/iationof the solenoid with differing current values.

Upwardly extended spring contact members 29 are secured tosaid stem 24:which are adapted in the extreme operated position of thediaphragm-engaging member to malte contact with suitable Spring contactmembers 80 upwardly extended from and secured to an insulating base 31,and which are adapted to be connected to the circuit to be controlled.

lt is desirable that after the diaphragmengaging member has moved upwardto force the diaphragm into the cup shaped opening in the pot 19 and toforce the air from between said pot and the diaphragm, as will behereinafter described, that means lbe provided, after the Contactmembers have been made to control the circuit connected thereto, torapidly admit air to the space between said poty and diaphragm andpermit the rapid return of the relay to its normal condition'inreadiness fora subsequent operation.

For this purpose a check or automatic in-l let valve 32 is arranged inthe pot 19 and serves, during the return of the diaphragm 2l to itsnormal condition, to rapidly admit through the leak valvedetermining'the time element.

Instead of providing a fluid tight diaphragm and a leak valve, I preferto omit the leak valve'and to form a yielding diaphragm of a suitablepervious material through which the air vmay flow at a suitable ratewhen said diaphragm is moved upward into the cup shaped opening of thepot 19.

The pervious diaphragm may be of any suitable material which willsatisfactorily answer the purpose. It may be for instance, of amaterial, as suitably compressed felt, which is uniformly porous asshown in Fig. l, or it may be of a material as gold beartes skin whichisimpervioiis to air and which lio khas a plurality of mechanicallyformed air openings or relatively minute pores or perforations L.l0therethrough, such for instance as shown in Fig. ll.. rlliese openingsor perforations may be arranged in any suitable or desi red pattern.

In connection with a porous or pervioiis diaphragm, I prefer to use adiaphragm-engaging member having a corrugated diaphragm contactino`surface or having a plurality of perforations therethrough.

In Figsi'l and 2, I have shown a substantially uniformly porousdiaphragm and a diaphragm-engaging member which has av smooth diaphragmcontacting surface. llith such an arrangement it is seen thatas thediaphragm-engaging member, is moved upward, it engages more and more ofthe surface of the diaphragm and so progressively closes the pores ofthe diaphragm. and thereby progressively restricts the flow of airtherethrough and consequentlyA the time 'element progressivelyincreases.

In Fig. 5, I have shown a diaphragm-engaging member 23 provided with aplurality 0f corrugations. The depth of these oorrugations is arrangedto be such that the dia-l phragm does not fill. the corugations and theactual contacting surfaces of the corrugations of the diaphragmis'arranged to be coinparatively small so that as the diaphragmengagingmember is moved upward into increasing contact with the diaphragm theflow 0f air from that portion of the diaphragm in contact with theVdiaphragm-eiigagiiig member is not appreciably retarded.

Inv Fig. 6, I have shown a diaphragm-engaging member 23 provided with aplurality of perforations l5 through which air is adapted to pass fromthat portion of the diaphragm in contact with the diaphragmengagingmember.l

It is evident that many modifications of vdiaphragins maybe employedthrough which the air is adapted to be forced in the upward movement' ofthe diaphragm and many forms of diaphragm-engagingl members may be alsoemployed in conjunction.`

tact with said diaphragm for its actuation i i having fluid passagestherein for the flow of fluid from said reservoir. l

2. A retardingdevice'comprising a fluid reservoir a fluid permeablediaphragm forining a wall Aof said reservoir, vand a diaphragm-engagingmember adapted to contactwitli said diaphragm for its actuation formedwith corugations therein for the flow'of fluid from said reservoir. 'Y

3. A retardation device comprising` a fluid reservoir.y a flexiblefluid-permeable diaphragm forming` a wall of said reservoir,

and a diaphragm-engaging member engageable with said diaphragm for itsactuation. In testimony whereof. I have signed my name to thisspecification, in the presence of the subscribingwitness.

` TALMA T. GREENWOOD. llVitness:

II. B. Davis.

